In the class of hearing aids generally referred to as implantable hearing aids, some or all of various hearing augmentation componentry is positioned subcutaneously on or within a patient's skull, typically at locations proximate the mastoid process. Implantable hearing aids may be generally divided into two sub-classes, namely, semi-implantable and fully implantable. In a semi-implantable hearing aid, components such as a microphone, signal processor, and transmitter may be externally located to receive, process, and inductively transmit an audio signal to implanted components such as a transducer. In a fully implantable hearing aid, typically all of the components, e.g. the microphone, signal processor, and transducer, are located subcutaneously. In either arrangement, an implantable transducer is utilized to stimulate a component of the patient's auditory system to cause or enhance the sensation of sound for a patient.
A number of different types of implantable transducers have been proposed. By way of primary example, such devices include those that utilize a driver, e.g. an electromechanical or piezoelectric driver, to move an actuator designed to stimulate the ossicular chain of a patient. By way of example, one type of electromechanical transducer includes a driver that moves an actuator positioned to mechanically stimulate the ossicles of a patient via axial vibratory movements. (See e.g. U.S. Pat. No. 5,702,342). In this regard, one or more bones of the ossicles are made to mechanically vibrate, thereby stimulating the cochlea through its natural input, the so-called oval window.
Orienting and positioning an implantable transducer for interfacing with a component of the auditory system, e.g. the ossicles, poses numerous challenges. For instance, during implantation it is often necessary to locate a transducer both laterally and/or vertically relative to the auditory component, and once located, maintain such location for an indefinite amount of time, e.g. during the life of the implant. Furthermore, implantable transducers include components, such as the driver and transducer electronics, which may be damaged by exposure to biological fluids, and therefore, it is desirable to limit exposure to the same. Providing an interconnection between a movable member, such as an actuator, and the transducer, however, that is both movable and sealed is difficult as such an interconnection necessitates forming a seal between the actuator and the transducer housing that does not interfere with driving or moving of the actuator in response to transducer drive signals.